Los Angeles-based Cadiz, Inc. and the Santa Margarita Water District (SMWD) in Rancho Santa Margarita, the lead agency on the project, plan to divert and store the groundwater over a 50-year period, then sell the water for commercial and industrial use for customers in South Orange County.

Cadiz owns 45,000 acres in eastern San Bernardino County, most of which overlies the Cadiz and Bristol dry lake beds comprising the Fenner Valley aquifer system. Cadiz and the SMWD plan to pump 50,000 acre feet of groundwater from the aquifers annually.

Opponents of the project, namely various environmental groups, say that amount would exceed the natural recharge rate of the groundwater basins and that springs within the Mojave National Preserve link to the aquifers and could be jeopardized should the project move forward.

Sen. Dianne Feinstein also has reservations about the project. In a letter to board Chairwoman Josie Gonzales on Monday, Feinsten said she continues to oppose the project after more than a decade, and urged county supervisors to oppose the project if the amount of groundwater to be extracted from the aquifers exceeds the natural annual recharge rate of the basins, which the United States Geological Survey (USGS) determined to be 5,000 acre feet per year in 2001.

Proponents of the project, however, say it is environmentally sound and would create much needed jobs.

Opponents and proponents crowded board chambers Monday during the daylong public hearing.

Michael LaBroad, southwest sales manager for Northwest Pipe Company in Adelanto, told the board the project is good for the county.

"As an engineer I believe (the project) is technically sound," LaBroad said.

The project already has triggered two lawsuits.

In June, Delaware Tetra Technologies Inc. sued the county, the Santa Margarita Water District and Cadiz, Inc., alleging, among other things, that the project would sap the groundwater from the Bristol and Cadiz dry lake beds, which the company's brine mining facility depends, and shutter its mining operation.

In August, the National Parks Conservation Association, Center for Biological Diversity, Sierra Club, and San Bernardino Valley Audubon Society filed a lawsuit in San Bernardino County Superior Court challenging the project.

Analysis by investigators retained by the environmental groups determined the average annual recharge rate of the basins to be 4,100 acre feet, while estimations by Cadiz investigators determined the average to be more than 30,000 acre feet.

In her letter, Feinstein said that even if the amount of groundwater extracted annually be reduced from 2.5 million acre feet over the project's 50-year life span to 1 million acre feet, as has been proposed, it would still be too much.

"I remain concerned because even with a 1 million acre foot cap, which translates to 20,000 acre feet annually, this amount still far exceeds the USGS recharge estimate and those of other independent groups," Feinstein said in her letter.

County spokesman David Wert said the county realized early on it could not take as gospel the word of either the project's opponents or proponents regarding groundwater recharge rates. Instead, the county set a limit as to how deep groundwater could be pumped: 80 feet below the surface.

Cadiz and the SMWD would have to suspend groundwater pumping if groundwater elevations decline faster than projected, according to a staff report prepared for the Board of Supervisors.